Spacial distribution and time variation in seismicity around the Antarctic Plate-Indian Ocean region

Spacial distribution and time variations in seismicity around the Antarctic Plate-Indian Ocean (0-160°E , 20-80°S ) is evaluated based on the data compiled at the global seismological centers since 1964. Seismicity in the oceanic area of the Antarctic plate, along with ridges/transform faults between the Indian-Australian Plate, represents characteristic features before and after large earthquakes, such as the Balleny Earthquake on March 25, 1998. Seismicity in the aseismic ridges immediately east of the Australia-Antarctic Discordance (AAD) increased the year before occurrence of the Balleny Earthquake. Long period variations in seismicity during more than 30 years imply several characteristic time periods of increase in cumulative seismicity, associated with dynamic distribution of tectonic stress in space and time between adjacent plates. Time variations in seismicity around the Balleny Earthquake region, in particular, drastically changed before and after the main shock in March 1998. The recent distribution of hypocenters in this area appears to extend toward Wilks Land, followed by the excitation of local events beneath the continental ice sheet of Antarctica. Seismic activities of these areas might reflect far-field tectonic stress in the lithosphere around the region

Locating earthquakes around Antarctica by using neural networks based on deep learning

The Tenth Symposium on Polar Science/Ordinary sessions: [OG] Polar Geosciences, Wed. 4 Dec. / Entrance Hall (1st floor), National Institute of Polar Researc

Changes in intracellular content of glutathione and thiols associated with γ-glutamyl cycle during sperm penetration and pronuclear formation in rat oocytes

The content of glutathione and other thiols in rat eggs was examined during sperm penetration and pronuclear formation by high-performance liquid chromatography with fluorescence detection. Reduced glutathione (GSH) content was higher in unfertilised oocytes (8.50 ± 0.29 pmol/egg) and penetrated eggs with a decondensed sperm nucleus (DSH eggs; 7.72 ± 0.56 pmol/egg) than eggs at the pronuclear stage (PN eggs; 5.93 ± 0.10 pmol/egg). The content of oxidised glutathione (GSSG) was not different among experimental groups (152.6 ± 74.1 nmol/egg in unfertilised eggs, 146.0 ± 50.0 nmol/egg in DSH eggs and 39.7 ± 17.3 nmol/egg in PN eggs). The GSSG/GSH ratio did not change during fertilisation. Although the reduced cysteinylglycine content of eggs did not change among experimental groups, the oxidised form of cysteinylglycine increased (p &#60; 0.025) between sperm decondensation (6.9 ± 1.5 nmol/egg in unfertilised oocytes and 10.1 ± 2.1 nmol/egg in DSH eggs) and pronuclear formation (40.5 ± 11.5 nmol/egg in PN eggs). Low contents of cystine were detected during fertilisation but cysteine and &#947;-glutamylcysteine were not detected in any treatment groups. These results demonstrate that GSH content in rat eggs decreases between sperm decondensation and pronuclear formation, probably due to the increased activity of &#947;-glutamyl transpeptidase.</p

Rayleigh-Wave Multipathing along the West Coast of North America

We have created a movie of surface ground motion for the 3 November 2002 Denali fault earthquake based on spectral-element simulations using crustal model CRUST2.0, mantle model S20RTS, topography and bathymetry model ETOPO5, and a finite-fault slip model. The movie features two anomalous wave packets that travel along the west coast of the North American plate following off-great-circle paths. These wave packets are Rayleigh waves with dominant periods around 20 sec, which are also found in seismograms recorded by the Southern California Seismic Network. One of these packets is the direct surface wave, whose group arrival time changes laterally as dictated by the shape of the Oregon coast. The other packet is a surface wave reflected by a lateral interface underneath the Rocky Mountains. A linear reflector parallel to the Canadian coast offsetting it by a few hundred kilometers can explain its arrival time, but the offsetting distance derived from the synthetic seismograms puts the reflector 350 km northeast of the result obtained from the data, indicating a need to update the crustal and mantle models in this area

May 30, 2015 Bonin Islands, Japan deep earthquake (Mw7.8) recorded by broadband seismographic station on Greenland ice sheet

第6回極域科学シンポジウム[OG] 地圏11月16日（月）　国立極地研究所３階セミナー

Low serum albumin concentration is associated with increased risk of osteoporosis in postmenopausal patients with rheumatoid arthritis

Background: The risk of osteoporosis in patients with rheumatoid arthritis (RA) is frequently overlooked, and investigating a simple indicator in routine care may be beneficial to motivate osteoporosis examination. The aim of this retrospective, case-controlled study was to identify the correlation between serum albumin concentrations and the prevalence of osteoporosis in postmenopausal patients with RA. Methods: This study enrolled 197 patients who underwent dual-energy X-ray absorptiometry of lumbar spine (LS) and proximal femur without osteoporosis treatment [mean age, 67.5 years; disease duration, 12.8 years; Disease Activity Score assessing 28 joints with C-reactive protein, 2.0; prednisolone dose, 4.9 mg/day (usage, 42.6%); and LS T-score, −1.9]. Patients were classified into 2 groups: osteoporosis, defined as ≥ 1 part bone mineral density T-score ≤ −2.5 or history of fragility fracture of the vertebra or proximal femur (121 patients), and non-osteoporosis (76 patients). Groups were then matched by propensity score using clinical backgrounds affecting bone metabolism. Results: In non-matched model, serum albumin concentration was significantly associated with osteoporosis-related factors such as aging, inflammation, physical disability, and glucocorticoid dose. Multivariate logistic regression revealed that serum albumin concentration was independently and significantly associated with osteoporosis risk (odds ratio = 0.22, 95% confidence interval = 0.08, 0.61, p = 0.0033). After propensity score matching, 57 patients for each group showed that in addition to the LS and femoral neck T-scores (p < 0.001), serum albumin concentrations (p = 0.01) remained lower in the osteoporosis group compared to non-osteoporosis group. Receiver operating characteristic curve analysis in non-matched model revealed that when cut-off value of serum albumin concentration for indicating osteoporosis was set at 4.2 g/dl, the area under the curve was 0.69, sensitivity 0.74, and specificity 0.58. Conclusions: Low serum albumin concentration was significantly and independently associated with the prevalence of osteoporosis, which may be considered as one of the osteoporosis-related factors in postmenopausal patients with RA.Nagayama Y., Ebina K., Tsuboi H., et al. Low serum albumin concentration is associated with increased risk of osteoporosis in postmenopausal patients with rheumatoid arthritis. Journal of Orthopaedic Science 27, 1283 (2022); https://doi.org/10.1016/j.jos.2021.08.018

Greenland Ice Sheet Dynamics and Glacial Earthquake Activities

第2回極域科学シンポジウム　共通セッション「大気-海洋-雪氷-固体地球の相互作用」 11月15日（火） 統計数理研究所 3階リフレッシュフロ

Japanese contribution to the GreenLand Ice Sheet monitoring Network (GLISN)

第3回極域科学シンポジウム/特別セッション「これからの北極研究」11月28日（水） 国立極地研究所 2階大会議